The invention relates to a motor-driven machine, which is in the form of a hand tool, with integrated suction dust removal, and in particular a saw. The drive motor of the machine drives a fan wheel of a suction removal fan. The fan wheel is provided with blades and rotates in an air guide housing. The front wall of the guide housing is associated with the mouth of the suction conduit, and the outlet of the guide housing is in flow communication with a collecting container, wherein the sucked-in chips can be disintegrated by means of a chip cutting means which is formed by the blades of the fan wheel and at least one disintegrating element which co-operates therewith and which is fixed with respect to the housing.
Such a machine is known from DE-C-943 970. The known motor-driven machine is preferably a planning machine in which comparatively large planning chips or shavings but also dust, splinters and the like are produced. In order to prevent the immediate working area from becoming dirty, those chips and the like, immediately after they are produced, are engaged by the suction of the suction removal fan and transported by means thereof to a collecting container or the like. However, because it is not desirable to have the dimensions of the suction conduit and also the suction removal fan unnecessarily large, there is the risk of a blockage occurring, in particular when dealing with large chips and with a high level of chip production.
In order to avoid the risk of blockage, the previously known motor-driven machine has a chip cutting means which breaks up the chips and thereby overall improves chip transportation. In the machine of the prior art, the chip cutting means used is a breaking or disintegrating member which projects inclinedly into an internal frustoconical cavity in the fan wheel. When the large chips are thrown against the disintegrating member by the air flow, they break up and that results in the desired disintegrating effect. By virtue of its comparatively large spacing and its shape as well as because of the lack of a cutting edge, the chips are not cut up by the disintegrating member but only broken up into comparatively large pieces. That, however, is not sufficient to prevent blockage of the suction removal fan and/or the air guide duct.
It is also known from DE 38 43 236 Al for an electric hand tool or an electric hand circular saw to be equipped with a suction dust removal device. In that arrangement, however, the chips are only sucked away and not reduced in size, so that here too there is the risk of a blockage occurring.